Non-interfering extension party-line telephone system.



L S- A? COPY T. s. MARTlN. NON-INTERFERING EXTENSION PARTY LINETELEPHONE SYSTEM.

APPLICATION FILED NOV. 25, 1905. 1,151,544, Patented Aug. 24, 1915.

5 SHEETS SHEET l.

T. e. MARTIN. v NON-INTERFERING EXTENSION PARTY LINE TELEPHONE SYSTEM.

' APPLlCATlON FILED NOV. 25, I905.

Patented Aug. 24, 1915.

5 SHEETSSHEET 2.

T G. MARTIN.

NON-INTERFERlNG EXTENSION PARTY UNE TELEPHONE SYSTEM,

APPLICATION FILED NOV. 25, 1905.

-1 1 5 1 54%. I Patented Aug. 24, 1915.

5 SHEETS-SHEET 3.

NON-INTERFERING EXTENSIUM PARTY LINE TELEPHON T. G. MARTIN,

E SYSTEM. APPLICATIQN FILED NOV. 25, 1905.

- Patented Aug. 24, 1915.

J SHEETS-SHEET 4.

T. G. MARTIN.

NON-INTERFERING EXTENSION PARTY LINE TELEPHONE SYSTEM.

APPLICATION FILED NDV. 25. 1915. v

1,151,544. Patented Aug. 24, 1915.

5 SHEETS-SHEET 5.

magi? @wjggggj UNIT D STATES PATENT OFFICE.

TALBOT e. MARTIN, or GHICAGO, ILLINOISMASSIGNOR, BY MESNE ASSIGNMENTS, r

arty-Line F1 51 TBU ST A ND SAVINGS' BANK, TRUSTEE, OF CHICAGO,ILLINOIS.

non mrnnrnnmenxrnnsrou PARTY-LINE TELEPHONE SYSTEM.

To all wiwm it mag/ cofncm'." I

Be it known-that I, Taneo'r G.-,MART1 N, a

citizen of the United Cook .gcounty', Illinois,

have invented a certainnewand useful Improvement in Non-InterferingExtension'or Telephone Systems, of which the following. is aspecification?- I y y invention relates to telephonesystems automatictelephonesy'stemsofthat type in which more or-less ofithe trunking or.other" switching'operations are produced by the calling-subscriberwithoutpthe aid of an0perator, and by; transmitting one or I moreelectrical impulses to the exchange'or central station, as for example,by momenarily grounding either one or both sidesf the line a t.'thef-subi-station of the callngsubscribeny In;extension-andparty-linetelephone sys-c tems'of the particularclass to which my fee inventionmore especially relates, it is evident that if one'fsubscrlber. is usinga hne WhlCl'l 15130111111011 toseveral subscribers, and

ifanother-subscriber on the same line attempts to use histelephone, theconnections already' established-- through the medium of 7 saidlinerwil-l'be broken-that is tosay, the

intruding 1 subscriber. will,

7 in attempting to use: his. telephone,

In such case, the intrusion of aYthirdsuba grounding of bothsides of theestablished line-circuitaand 'thus set up the conditions which arerelied upon as a means for rej machinery by which.- the circuit wasestablished. I'n-other words,-

storing the switching in extension and party-line telephone sys tems itis always undesirable to have the circuits and apparatus so constructedthat a third subscriber can listen-in on anestablished circuit andthereby overhear the con-- Vversation between the two subscribersalready in possession ofthe line; and inautomat-1c or semi-automatictelephonesystenis of that character in which electrical im-Specifieation of Letters Patent.

Statesof America, and

in general, butmore particularly-to the so-; called extension and partylia e' telephone systems, and especially toautomatic or semiject-to" thesupervision of being disturbed or molested by any other operate certainrelease-circuits 'and thereby release andrestore the 35' switchingdevices by whichthe talking cir--v uit was-established. Suppose, forexample, that one subscriber-0n a line isin conversation witliasubscriber-on another 'line, or with another subscriber on the. sameline for party line telephones,

scribe-r on the same line can use the latter Patented Aug. 24, 1915.

' Application-filedfiovember 25, 1905. Serial No. 289,048. I

pulses are used for calling the number of the called subscriber, and forreleasmg the switching machinery after ,the subscribers are throughtalking, itfis important and practically necessaryI find that someprovision-be made whereby when any .two subscribers are using a line athird subscriber cannot then manipulate his'tele phone sw tchlng devicesin such manner as to break or interfere with the circuit establishedbetween the said talking subscribers. It is obvious that this is true ofeither the so-called extension telephone arrangements in which severalextension telephones are connected with a main or master telephone, orof the ordinary party-linev arrangement in which several subscribers aresimply bridged across a' telephone line and not suban operator, at-amain or master telephone.

' Generally stated, therefore, theobject of "my invention is theprovision of an im proved and highly eflicient extension or party-linetelephone system so "constructed that the different subscribersoccupying a line in common cannot interfere'wltheach other in the use ofsuch lin e -that is, so con.-

structed that when one subscriber has the use it without any possibilityof line .he may subscriber.-

p Special objects of my invention are the provision of an improvedlock-out device whereby if one subscriber-is using the line no othersub-- for either switching or signaling purposes; the provision of animproved construct on and arrangement whereby several subscribers may beconnected with a, single line in an automatic or semi-automatictelephone systom, and whereby if one subscriber is using the line noother subscriber on the same line can transmit any electrical impulses,e ther for switching or-signahng purposes, or do anything which willendanger the continuity of the talking circuit established bythesubscriber already in possession of the line; the provision ofanimproved construction and arrangementwhereby the differentsub-stations on a' party-line in an automatic telephone system may eachbe provided with a 'locksoutor cut-oflf. relay. of such character thatno subscriber on the line can transmit any'electrical impulses, eltherfor switching 20 some other subscriber on the same line and theprovision of certain details and features phone system Yfirst-selectors,

or'signalingpurposes, while the talking circult is temporarily in use bysome other subscriber on the same line; the provision of a.

non-interfering partyline or extensionteleincluding first-selectorswhich are each provided witha special set of so-calledofi-normal-springs which are controlled by the selector-shaft, and bymeans of which the so-called rotary-lineconductor is maintained normallydisconnected from the non-grounded terminal of the battery, or othercentralized source of current, until after the shaft of the selec tor israised from its normal position; the

provision of an improved construction and arrangement, involving speclalrelays 1n the may call his own line, so to speak, so as to obtainconnection with the sub-station of of improvement tending to increasethe general efliciency and serviceability of party-- line and extensiontelephone arrangements of this particular character.

To the foregoing and other useful ends my invention consists in mattershereinafter set forth and claimed;

In the accompanying drawings, Figure; 1 is a diagram showing twoparty-lines connected together. One of said lines is provided with twosub-stations (#110 and #210) that are bridges in multiple across theline-conductors, and the other is pro- 'vided also with similar stations(#120 and 220). One of said lines is shown connected through afirstselector C and a "connector'D with the other of said lines, whichlatter .has bridged across it a second firstselector E. All of thesubstations shown are identical, as well as all of the first-selectors.Fig. 2 is a front elevation ofa substation keyboard mechanism, showingthe dial-plate removed and the switch-hook raised. Fig. 3 shows-the samemechanism with .the'switclrhook down. Fig. 4 is a diagrammaticperspective view of the firstselector C, showing the approximate relative positions of its parts, the switch-frame not being shown. Fig. 5 isa similar view of the connector D. Fig. 6 is a view similar to Fig. 1,in which the subscriber at station #310 has called and connected withthe station #110, on the same line, through the first-selector O and theconnector D, the station .#210 being bridged across the line betweensub-stations #310 and #110. a

All such sub-stations are provided with the usual'details essential tosubscribers stations of the class in question. Sub-station #110, forinstance, is provided with a receiver 2 and a switch-hook 3, whichlatter has radiating from its body a number of cainf-a 'ms 4, 5, 6 and7, 'said hook being pivand improved circuit con- -nect1ons,whereby aparty-line subscriber condenser 15, the latter being contact with thelatter.

ceiver is removed. The rotation is due to the tension "of a spring that1s not shown and the hook is pushed up for the purpose of changingcertain circuit connections to be disclosed. Furthermore, saidsub-station has a transmitter. 9, alocal battery 10, a ringer 11, aninduction-coil 12 wilh a primary winding 13 and a secondary winding 14,:a condenser 15, a lock-out magnet 20, and in addition a signaling devicecomprising a button 16, a spring 17,. and two contactpoints 18 and 19.When the switch-hook is down, the cam-arm 4 is held in contact with thespring 21, thereby flexingthe said spring in'a downward direction. Saidspring is normally in contact,- therefore, with, the arm 4, and in thisway completes the ringing circuit which includes the ringer 11 and thenormally bridged across the ine in series. Associated with the spring 21are two sets of springs 22 and 23, and 24', 25 and 26. Members'of each.of these sets, whenleft to their own ignsion, when the switch-hook isup, engage v contact witheach other-that is, the springs 22 and 23 arethen in contact, and the springs 24, 25 and 26 are in contact; butwhenever the switch-hook depresses the spring 21 the latter permits thesprings 22 and 23 to separate and forces, at the same time, the springs24, 25 and 26 apart,

'throughthe medlum of an insulating washer 27 located between thesprings 21 and 26.

. The arm 7 when raised, forces the spring 28 away from the spring 29,whilethe arm 6 permits the spring 30 (which is normally disengaged fromthe spring 31) to close in' Whenever the switch-hook is drawn down, 'thethree the release-springs, are forced into union by the arm 5 on said.sWitch-hook, which arm engages a laterally -projecting piece thatconstitutes the top extremity of the spring 32 of this group of springs.However, when the switch-hook nears its lowermost position the said armdisengages from said spring and permits the three to again disengage;The calling bytwo push-buttons 35 'and 36, two springs 37 and 38, twocontact-points 39 and 40, and the ground post 41. The lock-out magnet,as most clearly shown in Fig. 2, consists of the coil 20 mounted upon asupporting plate 55, which latter is secured to the keyboard frame 42.This magnet is provided with a is energized the spring 48 which normallyyoke 43 armature device is represented rests against said insulatingpinis pressed away from an adjoining spring 49. Furthermore, said magnetcarries on its under 1 front end of saidbrass piece is bent at a rightangle upward, and then at a right .angle to the. front, so that wheneverthe v armature -11 is attracted by the magnet the spring tension in thespring 51 forces the brass member upwardly until the angled sectionrises in front of the armature 44 and locks it in its attractedposition. The switch-hook also carries an angled plate 52 which has aprojecting section at the end of.

.which latter a slim rod 53 is hooked. This rod is very light and passesthrough an opening in the front part of a guide-post 54 which issupported upon the magnet yoke 43. The lower end of said rod works infront of the armature44 and is bent at a right angle horizontally and ina plane parallel with the surface of the armature. lVhen' theswitch-hook is depressed the said link is pushed down far enough todrive the lock 50 below the edge of the armature 44, which latter 'then,if the magnet is not energized, resumes its normal position, as

shown in Fig. 3. When said armature is restored the look-outmagnet-springs 48 and 49 resume their normal engagement.

As stated, the first-selector is shown in Fig. 4:, and may be .of thegeneral type de scribed in Patent No. 815,321, granted March 13, 1906,to Keith, Erickson & Erickson, This form of selector was well knownbefore the date of my application. It embodies among otherdetails thefollowing well known devices and circuits: the switch shaft 100, whichis situated on the front part of the switch, and on the lower section ofthe said shaft the line-wipers 101 and 102 are fastened, and just abovethem is a private-wiper, 103. These wipers are all not only insulatedfrom each other, but from the shaft as well. The positions of the wipersare opposite their respective banks-the line-wipers opposite the linebank 104, and the private-wipers opposite the private-bank 105. At itsmiddle portion the shaft carries a cam'106 which, being of a splitsleeve design, is tightened to the per section of this hub is smallerthan the lower and has formed in it a set .of circular or vertical teeth110 which are traversed by: a groove or slot 111. This groove 111 isdesigned to receive the bent and of'the vsocalled shaft support 112whichprevents. the i mally,

shaft from rotating unless said end is oppo site one of the groovesbetween the circular teeth. Still higher up the switch-shaft hasfastened to it an arm-like guide 113 which, when the shaft is .initslowest position," keeps the off-normal springs ll l'and 115 separatedfrom the contact-points 116 and i shaft are vertical and rotary and eachmovement musttake place at a different time.v By these movements thewipers may be carried into engagement with .any one of the hundredterminals or sets ofcontact-points that constitute the private andlinebanks. Since these contacts are arranged in ten vertical and tenhorizontal rows, the shaft is made to admit of ten vertical steps and ateach level of ten rotary steps.

The movements of the shaft are attained by means of the vertical androtary linerelays 119 and 120 and through-their respective armatures 121and 122 which control the springs 123, 124 and 125. Nor-- wipers areonestep lower than the lowest level of their respective banks, and onestep to the left of them. Now, when the vertical-line-relay ismagnetized, the verticalmagnet 126, which is composed of two coils 127and 128, is also magnetized. This last magnet has an armature 129 knownas the vertical-armature and which has projecting from it a so-calledvertical-arm 130 that has pivotally fasteneclto its end a pawl, 131,

known as the vertical-pawl, which is. properly adjusted to engage oneof. the circular teeth. 110 atieach vertical movement of thevertical-armature.

'the switch-shaft rests so that the This vertical-pawl isheld in normalposition by the retracting- I spring 132 suitably fastened by one end'tothe back of the pawl 131 and by the other to the vertical-arm 130. Thevertical-armature is provided also with a retracting-I spring 133between the pawl 131 and said vertical-armature that maintains thelatter in its position of rest.- The vertical-arm carries an L-shapedpiece 134 on its under side that assists in the unlocking of the switchwhen it is first brou ht ,into use. This L-shaped piece 134 pro ectsunder a link 135 known as the release-link, which latter is fastened byoneend to the armature 136 of the release-magnet 137. The release?magnet has assigned to it the' function -of restoring the switch to itsnormal position after it has been operated. This magnet is composed oftwo coils, like the vertical-magnet, but only one coilis shown. Therelease-armature, like the armature of all of the other magnets, issuitably supported, and is kept in normal position away from therelease-magnet pole-piece by a retracting-spring'138.

The forward end of the release-link 135 broadens out, and at thisbroadened section a square opening 139 normally engages with a lug 140on the double-dog 141. This dou-' ble-dog is pivoted 'on the switchframe by a points 162.

cured by arm 146, it

the pivots 142, and formed on its front part are two dogs 143 and 144that are designed, the first one to engage with the circular teeth 110,and the last with the longitudinal teeth 109. From the lower side of thedouble-dog a release-arm 145 projects downward and assists in therestoration of the side-switch when the switch is released.

vThe side-switch comprlses a supporting member 146 known as theside-switch arm. It is pivoted and may be moved about a vertical axispassing through the pivots 147. To the left of the pivots the arm 148extends rearwardly, and on the end of this arm the side-switch-link 149is pivotally seone end and at its other engages the lower end of therelease-arm 145, the end of the latter being of an inverted T-shape,while the end of the former is bifurcated. Still nearer to theend on thesame side, the side-switch-arm 146 carries a pin 150 which bindsin'toone piece four wipers 1 51, 152, 153 and 154 known as theside-switchwipers. These wipers are insulated from each other and fromthe'supporting pin to which. they are all rigidly fastened. The saidwipers being rigid with the pin, and the pin being also rigid with theside-switchfollows that when the sideswiteh-arm is rotated about thepivots 147 the side-switch-w'pers will move also. The right hand endofthe side-switch-arm is drawn out into a finger 155, known as theescapement-finger, that works in conjunction with a tooth-escapement tobe described: At the base of this finger-a forwardly-bent lug 156 limitsthe swivel movement of the side-switch-arm, and, therefore, of theside-switch'as a whole, by striking the cam 106 whenever out of itsnormal rotary position. If the rotary-line-relay is energized theprivate magnet 160 is energized as a result. This last magnet is usuallyfastened to a small private-magnet frame that is not shown and which isfastened to the mainswitch frame. Said magnet has an armature 161 thatworks in a vibratory manner about a horizontal axis that passes throughthe supporting The said armatureis formed with a forwardly-projectingarm 163 having two flat surfaces n1 an approxi ately portion of theprivate-arm,

.- shaped upwardly-projecting the shaft is rotated horizontal plane.Furtherm reftheend of thesaid arm is bent at a right angle downwardlyand carries certain mechanical details, namely, a lateral arm 164 whichis designed to control the relation of the privatesprings 165, 166 and167 and a tooth-escapement which includes two flexible springs 168- and169 each of which is riveted by one end to the arm 163, one on the upperside o and the other on the lower. The upper spring is straight and hasformed on its end a couple of tooth-projections 170 and 171 which extenddownwardly, while the under spring is bent at a right angle first downand then at a right angle to the front. This double angle on the lowerspring is so designed that the latter may against which portion saidspring rests with a degree of tension. There is space in front of saidbent portion to receive two other toothpieces 172 and 173 that areformed on theforward end of the escapement-spring and which aresustained in juxtaposition to the upper teeth,

clear the bent but slightlyto the rear thereof.' A retracting-spring174, which has one end attached to the private-armature and the otherend holds said armature the private -magnet pole-piece. With thisconstruction when the private-magnet is energized once, theprivate-armature is drawn down momentarily and restored. By thisoperation the escapement-finger 155 passed first from behind the tooth17 2 onto the rear of the tooth to the switch frame,

normally away from .170, at the downward stroke of theprivate behind thelatter tooth armature, and from at the return stroke. As soon as theescape ment-finger clears this last tooth, the retracting-spring 215draws the side-switch.

to the second position where it is stopped by the lug 156 striking thecam 106.

When the side-switcli-wipers pass to the second position, leaving thecontact-points 175, 176, 177 and 178, and engaging instead with thecontact points 197, 198, 199 and 200, the rotary-magnet 179 isenergized, this magnet being compos'ed of two coils 180 and 181. Therotating mechanism consists of the rotary-armature 182, a'circuitinterrupting arm 183 that works in conjunctionwith 7 twointerrupter-springs 184 and 185, the rotary-armature-finger 186 thatexercisescertain controlling influences over the privatearmature, andlastly the rotary-arm 187. This arm carries pivotally attached to itsforward end the so-calledv rotary-pawl 188.

Said pawl has attached to its rear end a small coiled spring 189, theother end of which latter is fastened to the rotary-arm, and whichalways restores the rotary-pawl to its normal-position. Upon each rotarystep of the shaft the -rotary-locking-armnl lt' I falls behind one ofthe longitudinal teeth by the rotary-armature retracting-sprin 190.Attention has been called. to the bank; that are located under theswitch parts in position before the line-wipers andthe pri--vats-wipers. The private-contact-terminals are each composed of but oneelectric conducting piece, but the line-contact-terminals are eachmadeof two metallic pieces, one over the other and insulated from eachthe wipers engage with the contacts of their respective banks, theprivate-wiper. with those of theprivate-ba'nk, and the linewipers withthose of the line-bank. After a switch has been operated it can bereleased by the energization of the release-magnet 137, whichenergization results if the line relays 119 and 120 are magnetizedsimultaneously, or if the back-release-relay 191 that controls the bac-release-relay-springs l92and 193 is energized. The circuits that arebrought into play under these conditions will hereinafter be more fullyexplained. When the release-armature is drawn back after therelease-magnet loses its magnetizing force, the double-dog is drawn awayfrom the shaft. rotated rests on the shaft-rest 112, as-previouslystated, and when left to the back pull of the-coiled spring 118 rotateson the said shaft-rest until the stop-arm 113 strikes the guide-post119the channel 111 that traverses the circular teeth, and leaves the shaftto fall to its normalfposition by reason of its own weight. Thevertical-line-conductor that leads to the first-selector C terminates inthe sideswitch-wiper 153, and to the same side switch-wiper the:vertical-normal-conductor 194 is connected, which normal-conductor leadsto and terminates in multiple-contacts in connectonbanks'. Therotarv-line conductor. 465, of the same line terminates in the ofi-normal spring 116 which is normally out of contact with thecorresponding spring 114, both of which springs are in engagementwhenever the switch is off-normal. The spring'll connects with therotary-side-switch-wiper 154. It will be noticed, therefore, thatbetween the rotaryline-conductor and the rotary-side-switch- ,Wiper'there'is a contact which is'normally engages with the longitudinal-'nates banks,

sideswitch'-wiper'152, after passing through er. When the shaft israised and rotated,

Said shaft when raised and. l

na-l of the battery. If f The shaft-rest then; enters open while theswitch is not in use. The rotary-normal-conductor 195, which alsoterminates in, multiple-contacts in connectorbanks, is connected with.the off-normal spring 116, and is therefore disconnected from therotary-side-switch-wiper 154. It

evertical andwill be noticed that,'like'th rotary normal conductors 194private normal conductor 196 in multiple-contacts at and at the selector0 in and l95, the

' connectorthe privatecertain private normal springs.

.also termi- The side-switch-wipers 151,152,153 and 154:, when in'thesecond positiomare 11113111 gagement, respectively, with the-l contactfpolnts 197, 198, 199 and 200; andwhendn the third position theseside-switch-wipers are in engagement with the contact pointsthe Contact?201, 202, 203 and 204.. Between point/.204 and the rotary line wiper 101the private-normal-rel'ay 205 is located and provided with an 208, so asto insure. the operations herein armature 206. which controls theprivate-normal-relay-springs 207 and after described. ThefirstselectoW-is, in addltion, provided with a bridge-cut-off-relay 209,the armature 210 of power to separate'the springs 211, 212 and 213. Thetwo'former of said springs constitute the terminals of the vertical. and

springs are separated one from the other, thereby opening the bridgeformed-between side switch contact-points 177 and 178, th inc-relays,and at the same time interrupting the connection between said relays onthe other side and the non-grounded termior any-reason the switch-shaftis raised normal spring closes with the contactpoint 117 a circuit isclosed through a' signal-lamp214. The retention of said shaft in araised condition uselessly is'undesirable since each station that triesto call while it is raised is locked outgfor the time. light signal isdesigned as switchboard man in charge of the exchange of anyirregularity of such a nature.

Fig. 5 shows the connector which has many parts and circuits verysimilar to'those of the first-selector, and the general movements arenearly identical. The connector may be of the scribedin. Patent No.March 13, 1906, to Keith, Erickson & Erickson. This form of connectorwas Well known before the date of my application. To the whichre'lay hasthe bridge-cut-cff-relayrough ,said

general type 'de-' 815,176, granted rotary line-relays 119 and ionvertically disposed switch-shaft 250 are secured the vertical and rotaryline-wipers well as the circular ratchet-teeth 257. The

latter are located just above the rotary ratchet-teeth, and aretraversed by ,a'longitudinal groove or channel 258, and in order tocorrespond with the number of levels shown in the bank 259, the saidteeth are preferably ten in number, so that the shaft may be given tensuccessive vertical steps, and so that it may be thus at each stepplaced at one of the ten levels. At each level, by means of thelongitudinal teeth,

said shaft maybe rotated ten steps. The

coiiperatewith the bank-terminals 259, and these terminals are arranged,of course, in ten horizontal rows of ten terminals each, in 4 the usualand well-known manner. The private-wiper 253 is adapted, on the otherhand, to coijperate with the bank of privatecontacts 260. At its upperend the said .shaft is subject to the action of a clockspring 261 whichhas one end secured to said shaft and the other to the stop ornormal-post 262, whereby the shaft when ro tated winds up said spring,and whereby when the switch is released said shaft may be automaticallyrestored to its normal position from any position in which it may havebeen temporarily held;- for the purpose of maintaining any desiredelectrical connection. The shaft is also provided at its upper endportion with the guide-arm 263 which normally keeps the spring 264 outof engagement with the stationary switch-contact 265, which latterconstitutes one terminal of the well-known busy machine F' that is, themachine for producing the current .used for giving the busy signal to acalling subscriber when necessary. Before the shaft is rotated from itsnormal position, the groove or channel 258 is engaged by the end of thehook-shaped arm or stationary shaft-rest 266; but with the shaft raisedto some desired level, and as soon as it is rotated, the circular toothat such level then slides onto said rest and rotates upon it instead ofon the vertical-dog 267. Thus the saidrest acts not only as a bearing,but as a support for the shaft as well.

The vertical and rotary line-relays 268 and 269 are bridged across thetrunk-lineconductors 'in' front of the condensers 270 and 271, asclearly shown, with the nongrounded pole of battery B-connected to thesaid bridge at a point between the two relays 268 and 269. Thevertical-magnet 6 272 is controlled by the vertical-line-relaydouble-dog is said line-wipers 251 and 252 are adapted to .289, 290 and291, audissubject tute the well-known switch.

rotary-magnet 293 has an armature 29.4 piy= ,mally away from 268 andarranged to operate the verticalratchet-pawl 273, which latter ispivotally mounted upon an arm to the armature 275.

arm 274 is provided with a short L-shaped arm 277 for operating therelease-link 278.

The latter, like the release-link of the first- 274 rigidly securedwThis armature 275. vibrates about the points 276. The vertical-1selector, has anopening 27 9' which normally engages the pro ecting pindouble-dog 281.

magnet ole-pieces by a retracting-spring.

280 on the, The said; vertieaharj p normally retained away-from thevertical-" The dou le-dog is provided with a. locking member 267 adaptedto-engage teeth 257, and also with member 282 adapted .to engagethe'longitudinal ratchet-teeth 278. spring tension that tends always toforce the circular another. locking 256 whenever... the, released fromthe release-link The said double-dog'is subject to the said projectingmembers ordogsinto en= gagement with the said ratchet-teeth, and s.

provided in addition with a-"downwardly- 1 extending arm 283 having aT-shaped end portion 284 adapted to support the '-bifurcated end ofithelink 285, which latter, has

its other end pivotally connected with the end of arearwardly-projecting member286 on the side-switch-arm 287i The saidsideswitch-arm is swingingly mounted and provided with the usualside-switch-wipers 288,v

he so-called to the for-y 292. The sideotally mountedat 295and-f'carries arigid I arm 296 upon pawl 297 has its support, the latterbeing pivotally mounted upon said arm 296-. IIt' the end of which therotary-'- I will be seen that the pawl 273 is adaptedthrough thecircular ratchet teeth 257 to actuate the shaft 297 is adapted with theaid of the longitudivertically while the pawl 3 If nal teeth to actuatethe shaft rotatively.

Both the vertical and rotary magnets are connected directly with pole ofthe battery and are controlled by the vertical-line-relay 268, subject,however,'to

the switching action of the side-switch-wiper The so-calledprivate-magnet e298 299, having two 288. provided with the armatureflexible springs 300 and 301 whichqa re provided, the upper one with onetooth 303,- and the lower one 'with two teeth 304 and. 305. \Vith theexception of the spring 300; having only one tooth the escapement deviceof the nongrounded the connectoris identical with that of the All of thearmatures ofthe first-selector, are held nor; y their respective magnetsture is pmvided with an insulating piece 307 that engages with theprivate-springs 308, 309, 310 and 311- as a whole, and which is adaptedto flexthe springs 309 and 310 up and down. These two springs areriveted together, but kept from electrical connection by anysuitable'insulating material. When the private-armature is depressed thesprings 3'08 and 309 are separated and the .retained in contact.

springs310 and311 are pressed into contact; while if theprivate-armature is raised the reverse occurs with-the .springs 308 and309 The side-switch-arm 287 is drawn out at one end to form the finger312 known as the escapement finger and adapted to coiiperate with theescape- Inent-teeth in releasing the side-switch from first to secondposition, 'in a well-known manner, and then from second'to thirdposition when the private armatufe-is depressed. The release-magnet 313has an armature 314 adapted, when attracted, to restore the double-dog281 to its normal position that is,'to a'position where the circular andvertical dogs 282- and 267 are held out of engagement with theirrespective ratchet-teeth 256 and 257. The side-switch-wipers 291 and-290 are adapted when shifted to third 5 position to establishconnection. between the line-conductors 483 and 482- and the line:wipers 251 and 252, respectively. The ringing-relay 315, by means of itsarmature 316,

controls through the medium of the ringerrelay-springs 317, 318, 319,320, 321, 322,

323 and 324 a number of circuits among whiclf are the connectionsbetween the condensers 271 and 270 and the wipers 251 and 252. After theconnector has completed a call and the ringer-relay is energized whenthe calling subscriber presses his signalingbutton and by so.doing'removes his own 4 subscriber.

line-conductors from the established circuit and substitutes instead theterminals of the ringer-generator H across the wipers 252 and 251 andhence across the subscribers line for the purpose of signaling thecalled The side-switch-wiper 289 is adapted when shifted into thirdposition to connect the private-wiper 253 with the groundedside-switch-contact 325. The sideswitch-wiper 288 is adapted whenshifted .into third position to connect with the ringer-relay 315, theterminal of which re- .lay is permanently connected to the contactpoint326.

In Fig. 1 the called first-selector E being identical to the callingfirst-selector C the parts will be recognized upon reference. Thevertical 'and rotary line-relays 401 and 402 are bridged betweentheside-switoh contact-points 403 and 404 with which the vertical androtary side-switch line-wipers 405 and 406 respectively engage while theside-switch is in the first position. These two relays are connectednormally,

terminates in the while the bridge-cutoif-relay is deenergized, throughthe" bridge-cutroif-relaysprings 407 and 408. 'At this point where twosprings are thus .in contact a third spring 409, connected with thenon-grqundbanks in'private-contact-points that correspond to theconnector line-bank-terminals in which the normal-conductors 501 and 502terminate. U'similar normal-line-conductors are indicated at 194 and 195and the private-normal-conductor at 196.

In Fig. 1 sub-stations #120 and #220 are substantial duplicates of thesub-station #110. Assuming that the four sub-stations shown in saidfigure have all of their receivers on their respective switch-hooks, asindicated at station #220, then if the subscriber In the first-selectorat sub-station #110 wishes to call the subscriber at sub-station #120 heproceeds first to remove his receiver 2 from the hook 3. Saidswitch-hook is forced up about the bearing 8, and when the groundsprings 30 and 31 close into contact the ground post 41 is therebyplaced in connection with the groundterminal G The circuit thatcompletes this connection extends from theground post 41 along theconductors 450 and 451, through the ground springs 31 and 30, conductor452, lock-out springs 48 and 49, conductor 453, to the ground terminal GIn the next operation the calling subscriber presses the vertical-button36 once and the rotary-button 35 once, then again the vertical-buttontwice, and the 'otarybutton once, and for the last time thevertical-button ten times, and the rotary-button once. In this way, thefirst-selector C is connected with a connector 1) and the latter is thenconnected by Way of the first-selector E with a line that leads to thesubstation #120. When the verticalbutton 36 is pressed once for thefirst digit the vertical-line-conductor 454 is grounded once, since thespring 38, which is removed from contact with the contact-point 40, is

brought into contact with the groimd post 41. Each time thevertical-line is thus grounded at this stagethe vertical-line-relay 119of the first-selector C is enersaid tor 456,bridge-cut-ofi-relay-springs 212 and 213, conductors 457, 458 and 459 tothe nongrounded terminal of battery B and to ground G. Thevertical-line-relay-armature is operated once and presses spring 123into contact. with the ground spring 124, and

thus .completes a second circuit through the vertical-magnet 126, whichenergizes the latter. The current in this case passes from the groundterminal'G through the springs 124 and 123 and through the conductor.460 to the private-springs 166 and 165, thence through the conductor461, vertical-magnet. 126, conductors 462, .463, 464 and 459 to the.

non-grounded terminal of. battery B and to ground G. Thevertical-magnet. attracts its armature l29once and raisesthe shaft 100one step in the manner already described.

. It may be stated atthis juncture that if the calling subscriberdecides not to complete 30' the call he may restore the first-selectorthus disturbed, by simply restormgmhe receiver to theswitch-hook.

,. It has been describedthat inits action the switch-hook, throughthe-arelease-cam-arm 5, as it passes down, flexes the release- I springs32, 33 and 34 intocontact for a moment. One ofsaid springs-spring 32-has'the shape, somewhat, of ,an inverted L, and 4 it is so located that'asthe cam-arm descends the latter engages the protruding section ofspring,pressing it to one side, and

through itpressing the other two springs 33 and 34150 these threesprings causes the rotary and vertical line-conductors .454 and 465 tobo moment rily grounded at the same time. The eff: conductor is alreadyknown. :The r6taryline-conductor thus grounded, after the first-selectorswitch-shaft 100' is raised from its/normal position (by which act theguide-arm 113 permits the springs 114and'. 116 to come into contact)causes the .rotaryline-relay. 120 to be magnetized. 'Theath B of thecurrent through the verticaline-.-' relay, in this case, is from groundterminal G through'the conductor 453, lock-out re-' "lay-springs 49 and48, conductor 452, ground springs 30 and 31, release-springs 34, 33 and32, conductor 466 to the contact-point 40.and

the spring 38 to the vertical-line-conductor,' and thence through thevertical-line relayv 119, as above;

The circuit through the rotary-line -'relay extends from the same drawthe spring 166 from engagement with q r a moment-into electricalcontact." The temporary union -or engagement of,

ct of grounding the vertiealdine ."ipd'ihtd .comesflmagnetized itattracts the release ground terminal G to the release-spring 34 andthence to the release-spring .33 and through the conductors 467, 468 and469 to the contact-point 39,'over the spring 37 to therotary-line-conductor 465, ofi-normal springs 116 and 114,- conductor470, sideswitch-wiper 154, contact-point 178, conductor 471,rotary-line-relay 120, conductor 472, bridge-cutolf-relay-springs 211,212 and 213, tothe non-grounded terminal of battery B and to ground G.Whenever the rotary-line-relay 126 becomes magnetized its armature, 122,when attracted, fdrces the spring 125 against the ground spring 124, andthus closes a second circuit that includes the private-magnet 160. 'Thecircuit extends from the ground terminal Gr through the springs 124 and125, conductors 473 and 474, thence through the privatemagnet 160, andthrough the conductors 475, 464 and 459, thence to the non-groundedterminal ofl battery B and to ground G. The private-armature beingattracted by the private-magnet causes the arm 164 to withthe spring 165and closesitinstead with the thirdspring 167. Therefore, when the release is initiated, the line relays 119 and- 120 become energizedsimultaneously; and

since the private magnet energizes as a result of the energ'lzation-ofthe rotary line relay, the energizing'circuit for the vertical magnet126 .is broken when the. private springs and 166 separate, and,therefore, v the'said vertical magnet 126 does not ener- 1 0 gize atthe' release. But as the private spring 166,. which is connecteddirectly with the line relayspring .123, is shifted into'engagement withthe private spring 167, the operation of the vertlcal line relay 119causes the. energization. of the release magnet 137, since the privatespring 167 is directly connected to said release magnet. It .is thevertical line relay. 119, therefore, that directly Y causes theenergization of the release. niag- 110- net;-'137 by'establishingacircuit from the grounditenninal "G2 -through the ,line-relay- Springs124' and-.123, conductor 460 to the private-spring 166, asbefore;butfrom'hereitthen' takes a new. pathithrough the lower private-spring167, to :the conductor 476 amemem to the release-magnet'137, and. thenceover-til a 'oonduc'tors 462,'463, 464 and awe 1+ Y groundedterminal'ofbattery? G. Ofcourse, as. already 1 ut,-;.when I saidrelease-magnet -be'-' ar-mature {136 Land. throws the. release link 1'35Y9 thejiug 140. of thed'ouble dog' 1 41 which, asf 'soonias therelease-magnet becomes 1 second position by the retracting-spring 215,-

.returns to its normal from engagement with the circular ratchetteeth110. The shaft thus being deprived of its only support falls toitsnormal or lowered position and the release or restoration offirst-selector be assumed, however, that the subscriber instead ofreleasing continues his call by pressing the rotary-button- 35 onceafter the first-selector-shaft has been raised one step. Under suchconditions, the rotarylinerelay 120 is then magnetized once by acurrent. flowing from the ground terminal 1 -130 the ground post 11,thence through the spring 37 to the rotary-line-conductor, and throughthe rotary-line-relay to the nongrounded terminal of battery 'B and toground G. The energization ofthis relay causes the magnetizing of theprivate-magnet 160. Upon the downward strokeof the private-armature 161,the escapement-finger- 155 disengages from the rearmost tooth 172 of theescapement on the private-armature and falls against the upper rearmosttooth 170 from which the said escapement-finger disengages' in turn asthe private-armature position. Clearly, at this instant theside-switchis drawn into the and the lug 156 strikes the cam-piece 106,by which means the side-switch-finger is retained between" the,escapement-teeth 173 and 172.

At the instant that the side-switch-wiper 151 closes with thecontact-point 197, the magnetizing side-switch-wiper 151, conductor478,- the rotary-magnet-coil 181, interrupter-sprin 184 and 185, rota-magnet-coil '180, conductors 463, 465 an 159' to the non-groundedterminal of battery B and to groundG.

The rotary-armature 182 is thus attracted by the rotary-magnet 179 andthe shaft 100 is rotated one step by the rotary-pawl 188. At the sametime the privatesarmature is depressed by the rotary-armature-finger186, andvthe interrupter-finger, just as the rotary-armature strikes therotary-magnet.

polepieces, separates the interrupter.- springs'184 and 185 and thusinterrupts the magnetizing circuit. By the time that the, circuit isinterrupted,-however, the dog 144:

has engaged with the longitudinal teeth 109,

falling behind the first one of said longi-' 'escapement-finger and thelatter then falls into engagement with the upper foremost tooth 171'fromwhich it disengages as soon is accomplished. It will.

circuit through the rotarymagnet 179 is completed from ground G to thecontact-point 197, thence through the as the privatearmature is-restored by the" rotary-armature retracting-spring 190. As.

springs will again reeengage andthe energlzin circuit throughtherotary-magnet would be reestablished were it not that by the time thatthe reengagement occurs the private-armature escapement has permittedthe side-switch to. pass into third position,

no onger in contact withthe contact-point 197. As soonas theside-switch. passes into third necte and, therefore, theside-'switch-wiper 151 isosition the private-wiper 103 is con- A h toground through the conductor 479,

back-release-relay 19 1, conductor 480, sideswitch-wiper 152,contact-point 202, Y to ground G. This connection to ground provides theprivate-contact-point with which the private-wiper is connected withguard: ing potential, as well as all other. -rivateconltactointsconnected therewith 1n multip e. rotated by the rotary-armature theverticallocking-dog 143 is withdrawn from engag ment with the circularteeth 100 when the said rotary-loo I crest of the longitudinal toothover which it must pass. But at the same time the rest king-dog ridestoward the so t will be seen that as the shaft is 112 moves intov enga'ment with the circular teeth and: shaft, in lieu; of said yo 7' andremains thus in a support and .bearingas, ong as the shaft is retainedinitsrotary, laced condition, The side-switch now-being'm-third positionand the line-wipers.;being in engagement with the first terminal of thefirst level of ocking-dog,

es" 1:131 8553011 for the ment, acting as.

the line-bank, thesubscribers line is extend- Y 'ed' to the line-wipersand thence b way of a trunk-line,"'sim1lar to the trunke leadingv fromthe tenth terminal of the first level of the. line-bank (the conductors482, 483

and 519 of. which are shown), to an idle 1 connector. However,the-rotation of the shaft 'is not always terminated when theline-,wipers engage with the first set of con-' tacts. Forinstance,should there be atone time ninefirst-selectors each one usin tacts ofthe first row, for reasons similar to one'of the first nine trunks ofthe first leve those described in connection with the firstv selector C,when the side-switch of the latter assed intothe third'positio'n, sincethe si e-switch wiper 152 became. engaged with: thegroundedpontact-point 202..

1 the nine contracts of-the levelofthe same-group tobe connected toground, then when the calling subscriber grounds the rotary side of theline by press- ,ing the rotary-hutton'35 the 'sfid'e-sw itchtrips intosecond position, ltl'ca n be shown that because the jfirst nineprivate-terminals are supplied with a guarding potential rotation of theshaft will continu'e until the"wipers ment with the first'contact of thefirst level of their respective ibanks, and the privatearmature isdepressed by the" rotary-armature-fingen and at the same time theinterrupter-springs 1845 and 185 are separated by the interrupter-finger183. The first privatebanlr-contact with} which "the private-wiperengages; at vthe fir'st. step beingconnected .to ground, as.eit'plained, the private-magnet becomes energized. This energizingcircuit extends from th e grounded terminallofthe batteryB;throughthe'privateetsiiper of the switch that is occupying the firsttrunk, of

i the first-level and through the bank multiplying conductors to thecontact-point with which, the private-w per 103 is, engaged,

thence through the T privatewiper 103, conductor 479, the winding. ofthe back-release relay 191, ,conductor..{180,, side-switch-wip'er 152,contact-point. 19 8, conductors481 and 474, pv yate magnet 160,conductors 47 5, 464 and-459v to the non-grounded termina -Lei batteryband, to ground'Gr'. The privatearmature is thereby retained .depressed,even after the rotary-finger returns to its normal position in responseto. the retracting tension ofthe f rotary-armature F retractingv spring190;- Thenassoon as the interruptersprings;.-rei=lngage the circuitthrough the;

rotanysmagnet is once more closed and the 'shaft:,is,rotated one morestep by; the reenergization oi ithe said" rotary-magnet 179. The privatewipennof, course, 'is' driven into engagement with the-second contact ofthe first level "of'the-private-bank, and the line- Wipers intoengagement with-the second set of terminalsof the line-bank; but*still'the privatswip'en meets, another point with guardingpotentiaiwhich causesthe privatemagnet; to retain the ,private-arm ;t1-e attracted even while the 1rotary-a1 ;mature v returns to-i normal,thus retaining the side'- switch'in its second position. Thus forasecond time theinterrupter springs 18 3; and 185 are: separated-by theinterrupter-finger, as the rotary-tarmature'is attracted, and the n asthe rotaryarmature. 182; returns rgto its normal-position 'once miorethe-.interruptersprings closeaztogethere C1ear1y,f, then,; the shaftwillbe rotated in a step by step' manher as longgas theprivateewipercontinues to meet the grounded ,private-ibank-contacts. Q

After having 'I'Jeen" rotated onto "the ninth contact theprivate-wiperis rotatedone more step into engagement with the tenthcontact of the first level but, this last contact being without guardingpotentiahassoon as said private-wiper leavesthe ninth contact, themagnetizing circuit of the private-magnet that has up" to this time heldthe side-switch in thesecond position is then broken. This occurs atjustabout the 'point when the rotary-armature is-at the 'end of itsattractive stroke."This being true the privatearmature does not at:;onc'return to its normal position, but follows up the"rotar'yarmature-finger186 as the-latter returns to,

its normal position. At a given; i t th esc'apement fingerwhich has,during its 0 operation, been resting againsttheforemost tooth of theupper escapement-spring, leaves said tooth, and the side-switch as awhole-is brought tothehird pOsitiOn-bythe sides' witch retracting spring215, before the interrupter springs 're-engage; -'The -sid eswitch beingin its third ipositi'omth'e subonly as far asq-the first-selectorsideswitch-wipers 153 and154,'before" the sideits third position, is nowswitch sprang int line-wipers 101 and 102.

extended .tothe ticallyand' rotated ten points the'subscribers line isnot onlyextended to the saidwipers 'hut'through the rotary and verticalcontacts 'ofthe tenth terminal ofthe first level to the.trunk-conductors 482 and 483,. and to "thd if connector 3 D, asshown'i'n Fig. '1.

From the [description that has preceded,

it'should be clear that thefirst ground jimpulse to herotary line startsthe. selector scribers line which was originallyelite'nded IJTheshafthaving been'frai'se'd one step ve'rrotating, which rotation may continueautomatically until a. connection is" established with an idle trunk, Itwill be understood,

also, that if'while therotation of the shaft is taking pl cejthe sbscriber, should decide to check'.the.;progress of his call he'may're-,"st ore'th'e" first-selector by returning his receiver to its book. Asa result, the rotary and. vertical line-conductors, in a familiar'manner, are grounded. Since the side switch is, however, inse'condposition, and .as the vertical line conductor 4=54:1is-therefore' openat this time, the grounding of the verticalline conductor neednot beconsideredj;, but the rotary line conductor a 165, however, is connectedwith the .vertical-lmerelay 119;throu' hthe'springs 116 and'114,

.conductorl470, 'siders'witch-wiper 1545,. 'contact-point, QOQand;conductor 15 5, and,'si nce 1, 1 private-,magnethwhile the private-wiperis-passing o'v'er' grounded contacts,'is re- .tained magnetizedduringsaid 'rotatiomjthe 1 private-springs 166and 1 6'.7 .are maintainedclosed in contact." The switch is released as hi l bws G o nd g the r y11118 W i e ground G at the sub-station-to the releasespring 33, overthe rotary-line-conductor the side-switch is in the second positionproduces a magnetization ofcthe vertical-line relay while theprivate-springs 166 and 167 are together, bringing about, as a resultpreviously pointed", out, a magnetization of g the release-magnet 137;The energizing cir-i cuit of the ,vertical-line-relay extends from 465to the side-switch-wiper 154, through the vertical line-relay 119, andthrough the bridge-cut-oilf-relay-springs '212 and 213 tothenon-grounded; terminal of battery B and to ground G. Therefore, thereleasing from the'energizing of the vertical-line-re contact-points 177and 19.9 permanently, and

" the selector is released before the opera; tion is terminated, sincethe private-magnet during said rotation maintains the prlvateof thefirstselector while the side-switch 1s 1n second positionthat is, whilethe rotation of the shaft ,is taking place -results lay at the groundingofthe rotary-line conductor. This is a novel-feature ofimy invention andone which is desirable. It has been customary to connect the side-switchthe contact-points '178 and 200 likewise, the

.vertical-line-relay terminating directly in the first two, and therotary-line-relay in 'the last two. Then, while the shaft is rotating,and while the side-switch is in second,

position, if for any reason the calling sub; scriber grounds hlsvertical-line-conductor springs 166 and 167 in contact, To obviate thisdifficulty in the first-selector the'contact-points; 17 7 and 199 aredisconnected, and the contacts 178 and 200 as well, and be:

sides an extra conductor 494 connects the contact-point 17 7 with thecontact-point 200 to enable the switchto perform the release inthemanner just described. But after the f first-selector has onceoperated, and the side-switch is then tripped into third. posi tion',none of the line-relays remain longerin connection with theside-switch-wipers 153 and 154, since there is no connection be-. 1

tween the' adjoining ..contact -points over i which said wipers slide. aAfter the first selector-shaft has been rotated onto the "tenth contact,and the side-switch has passed. to third position, the callingsubscribers line is extended to the. connecto r D over thetrunk-conductors. 482- and 483 that terminate in said tenth terminal.Then the release .or restoration" bf said first selector? is attainedby. means of .the socalled back-release-relay 191-. Thelines beingextendedito the. connector, as shown in Fig. 1,- when the subscriber;again resses the "first button twice, "for. the secon digit,

he. thereby; again grounds .the verticaLline conductortwice,anfdtherebyoperates the- 3 'verticahline-relay 268- of theconnector,

twice. This last-ener 'zing the "circuit, begin-f the sub-station #110,extends to the ground post 41, and then passes through the spring 38 andextends over the vertical-line-conductor 454 to thevertical-side-switch-wiper 153 ofthe selector C, thencethrough thecontact-point 203, the conductor 484,- and the line-wiper 102, to thetrunk-conductor 482, vertical line-relay 268, conductors 485,

486, 487 488, 489 and490 to the non-groundedterminal'of battery B and toground G.-

- When the vertical-line-relay'of the connector attracts its armature326, the latter causes the connector line-relay-spring 327 to be pressedagainst the ground spring 328.

The vertical-magnet 272 is thereby energized twicein consequence, andthe connectorshaft 250 is raised two steps. This last en.- ergizingcircuit. may be traced from the ground terminal G, through the springs-328 and 327, the conductor 491, privatesprings 309. and 308, conductor492, sideswitch-wiper 288, conductor 493, verticalmagnet 272, conductors.487, 488, 489 and 490, to batter B and toground G. Of course, at therst movement of the verticalarm 274,'the release-link 278 is disengagedfrom the double-dog 281 by the L-shaped piece 277. The circular teeth atthis point, are so raised that as soon as the double-dog is liberated bythe removal of saidreleaselink the double-dog retracting-spring rotatesthe vertical-dog267 into engagement-with one scriber again presses ofthe ground post 41 to the rotary-lineconductor 465,, thence through thefirstselector-spri-ngs 116 and 114, conductor 47 0,-

sideswitch wiper 154, contact point 204, conductor 495, private normalrelay 205, conductor 496, rotary-line-wiper 101, rotarytrunk-conductor483, conductor 497, ringerrelay-springs 324 and 323, conductor 498, ro-

tary-line-relay 269, conductors'486, 487, 488,v

489 and 490, to the non-grounded terminal'of 'rbattery B and to groundterminal G. I When.

the rotary-line-relay is thus magnetized once the rotary line relayarmature' 329; is attracted once, which.- latter then "forces thesprings 330 and 328 into contact. This last operation closes [a];magnetizing" circuit through the, private-in'agnetr298. Said circuit'may be traced from' the groun'd termi- TnalG through the springs 328and33g, con? operation here is once. The escapement-finger, by the tensionof the retracting-spring 292, passes, during the attraction andrestoration of the pfziyate armature, from behind the escafementetooth305 to its second position-in rent of said tooth and behind the nexttooth304,but not quite in contact with the Patterbecause the cam-lug3,31 rests against the cam 254;. The the same as that described inconnection with the movement of the sidel switch in the first-selectorr.C. The side- ;switc'h' being thus changed from its first to itssecondp0sition, the; side switchwiper I Said relay, upon times, presses thespring the spring 328- again ten times. The rotary- 288ai-is rotatedpulsations over p through contact-point 332 onto the' contact-point Now,when the subscriber pressesthe vertical-button- 36 ten times, insteadof'the verq magnet 293 is actuated. The ten ground thevertical-linerconductor energizes the vertlcal-line-relay ten times.

magnet is, 1n-this way, energized ten times,

through the circuit that begins with the ground terminal. G and extends,as. above,

the springs328 and 327 to the sideswitch-wiper 288,,thence since saidsideswitch-wiper isi-n the second-position through contact-point 333,conductor 500, rotary -magnet'293, conductors 489 and 490 to the-- non'grounded terminal of battery B and to ground G. The armature 29 1 of therotary-'- magnet is attracted ten tudinal tooth over Of course, it willbe understood that by y it is attracted the rotary-pawl engages with oneof the longitudinal teeth 256"and rotates the shaft ten steps, one'stepat a time, inthe same way that the first-selector rotaryinagnet rotatedthe firstselectorshaft.

At the first rotary step of the shaft, the.-

shaft-rest 266 en ages with the circular teeth and catches t eshaft-when the vertical-dog 267 is drawn out of engagement with saidcircular teeth at the time that'the rotary-dog 282 reaches the crest ofthe longiwhich it hasto pass.

' thetime the "rotary-armature. strikes the the forward rotary action ofthe shaft the same time that the cir cular teeth pass into engagement;with1the shaft-support 266, the shaftl wipersfimove, onto. the first,conta'ct'of. the second level- 0f I At the second step" onto thesecondfcone said. wipers are moved t vvedterminal ofthe battery 13 andto ground 'is retained. At

pole-pieces the said rotary-dog drops into locking engagement withthelongitudinal teeth and provides a', means by. which their respectivebanks.

. tact of the-same level; andlsoonii Stepiby! L step,i1ntil'theyreachthegtenthcontactaThe; 4

from engagement with the tic'al -magnet' being energized, the rotary-'attracting its armatureten 327 in contact with relay-springs thecondenser times and each timeside f switch wiper wiper 1253, themethrough the;.private-nor mal conductor 507 (through the private nor- Icircuit through the rotary-magnet is not in terruptedf by any automaticdevice like the circuit of tne rotary-magnetof the firstselector; buteach energizin impulse through said magnet is pro uced and brokendirectly by the action of the subsciibenqjust as the vertical-magnet isen'er-' gi zed. The last step of the calling subscriber in completinghis connectionis te again ground the rotary line-conductor oncebypressingthe rotary-button 35 once; and again the'rotary line-relay isenergized, and

again the-private-magnet 298 impulsively attracts its armature once. The5- tft having been rotated, and the cam 2 having passed out of the wayof the cam-lug 331, f

the side-switch, finding no upper front escapement-to'oth, such as theside-switch of the first-selector encounters, passes into thethirdposition at the depression of the private-armature. In thethirdlposition', of

course, the side-switch-arm rests against the side-switchstop 334,wipers 288,289, 290 a'nd291 pass into engagement respectively 'with' thecontact-.

points 26, 325, "336 "and "337. The linewipers having been rotated onto'the tenth set; of contacts: of the second levelbf the bank 259, whichset constitutes the terminal "of the normal-conductors 501 and 502, and,therefore, ofthe sub-station #120, are thus put in electrical connectionwith the desired line. The vertical-line-wiperis connected with thevertical-trunk-conductor 482 by the conductor 503, andthrough theringer- 318 and 317, conductor 504 and 270 and the rotary-line-wiper 251is connected-with t e rotary-trunk-conductor 483 through. he conductor505, ringer-relay springs 321 and 320, conductor 506' and condenser 271.At the instant that the side-switch-wiper 28.9 comes into engagementwith the grounded contact 325' a'guarding potential is put on the tenthcontact of the second level of the private-bank which contactcorresponds with the line-terminal While the side-switchof the calledsub-station #120. No other connector may then venture on the said 'line.Furthermore, this guarding potential energizes the bridge-cut-ofi-relay4:18 of the E,.which relay, by its armature, 'icontrols I the' bridgecutofi -relaysprings 107,- .408 and 409., The magnetizing current whichpasses I through this relay comes from :the oun'dedterminal of batteryB' togroun -;G .-at the'connector side switch, to the side switchcontact-point 325,

' 289, and to the private i'idgecut-oif-relay 418, to the non ground-The object of energizing said relay is to by reason of the Y when therotary force apart the said springs for the purpose of removin thehon-grounded terminal of the battery B from connection with thevertical-line-relay 401 of the called first-se- 5 lector. Th1 connectionbetween these two lines having been established the calling .party isnow ready to signal the sub-station 120. If for any reason the calledline had been re bus v-for instance, if any of the sub-stations on theline, assuh-station #220, had been using the "first-selector E, or hadany other connector been in connection with the said line-there wouldhave been a guarding po- 15 te'ntial at the tenth private-contact of thesecond level of the private-bank, said contact corresponding to thetrunk-line that leads from the tenth terminal of the second level of theline-bank. Were the said line busy first-selector E being thus in use,the 'said private-contact and, of course, ,all other contacts inmultiple with it would'then be connected to ground at the instant thatthe side-switch of said firstselector passed into third position. The

circuit extends from the said private-bankcontact over the conductor 507through the private-normalrelay-springs 414 and 413, conductor 508,side-switch 416, to the grounded terminal G. In' the other case,

had some connector called theline in question, the said callingconnector, by means of a side-switch-wiper similar to the side--switch-wiper. 289, when said side-switchwiper is in third position,would connect the prit'ate-wiper and, therefore, the private-contact inquestion with a source of v guarding potential. ,Suflice it to say,howpressed his rotary-button for the last time,

to cause a switching. operation correspondin to the digit 0, theconnector D woul have been released and the calling subscriber wouldhave failed to make the'desired connection; for the releasing-of theconnector would have resulted from' the energization of the connectorrelease-magnet 313, the

side-switch being, of course, in the second position, which-1s theposition in which the.

side-switch should be before the rotary-lineconductor is grounded" forthe last time.

releasing magnet is energized extends from the ground terminal of thebattery 3 through paths already described to thetenth contact of thesecond evelof the connector "private-bank, thence through the private- 9wiper 253, side-'switch-wiper 289, contactpoint 335, conductor 510,private-springs 310 and 311,.conductors 511 and512, releasemagnet 313,to the non-grounded terminal of battery B and to ground G. Of course,line is grounded by the ever, that had there been such a guardingergizmg this rela Theconducting circuit over which the said callingsubscriber, the private-armature is attracted by the private-magnet overcircuitspreviously pointed out, so that the privates rings 310 and 311are pressed in contact.

he connector release-magnet being energized, the release magnet movesthe doubledog 281 in such a manner that the lug 280 on said double-dogis caught and held in the 279 on the end of the release-link openm 278.en the double-dog is thus rotated the. locking-dogs 267 and 282 arewithdrawn I from the shaft, which latter is then free to arated from thecontact-point 18 and closed m-connectionwith-the contact-point 19. In,

this way the vertical-line-conductor is connected to ground by way ofthe ground s rings 31 and 30, from the ground terminal and thence to thecontact-point 19 and through the ring 17, secondary circuit springs 22an? 23, contact-point 40, and

s ring38, thence to the vertical-lineeconactor 45 1. The connectoribeingreleased,

and the side-switch, of course, having been driven by the release-arm283 back into its first position, about its pivots 345, and with theside-switch-wipers 288, 289, 290 and 291 in en agement respectively withtheir correspon ing contact-points 332, 338, 339 and 340, and, ofcourse, with the escapement-ifim ger 312 behind the rearmost lowerescapement-tooth 305, the efiect of grounding the vertical line is tooperate the vertical-linerelay. As above described, the effect-of en atthis time is to raise the shaft of the connector vertically, whichmotion the normal-arm 263 permits the normal-springs 265 and 264 to comeinto contact. At this instant a busy. signaling current, originating ina suitable device comprising an induction-coil 341;, is sent over theline to the calling subscribers station and through his receiver, saidbusy signal notiiying him that the desired line is busy. The saidinduction-c0i1'341 comprises-"a secondary winding'342 into whichthebu'sy signaling cu'rrent'is induced.

When the busy circuit is closed with the calling station #110 thecurrentpasses from the 0011 342 through the conductor 513 to thecontact-point265; thence by way lof the spring 264, conductor 514,contact oint 340, to the side-switch-wiper 291, and t ence throughtheconductor 515, ringer-relaysprings 321 and 320, conductor 506, condenser271, conductor 483,- rotary-line-wiper 101, private-normal-relay 205,.conductor 495, side-switch-wiper 154, conductor 470,

springs 114 and 116, rotary-line-conductor ice 465, I 37; cOntact-fiint- 39', "condenser 15 ,='receiver 2,"secondary Wiiiding'l of thevertical-line-relay' 268 conduct011sf485 486, i 487, 488 and 489nant1back again'to thecoil 10 342. But, as-expl ained, instead ofthe call ingsubscriber-meeting a'glia 'ding p'otj ,I 1 t i" 1,1, he coi'nplet'eshisconnection the ii'tu i er described; and upon proceeding, he presses hissigndling-lbntton 16 and the ebygrounds connecting it the vertical-lineeondn'ctoi H v "withf the grounte1 minaI through the Springs i d lnctavj fio n l 1 spr 17, and spfi igs 22 'ang1'23, contacfipoint 4;0 to

' the said w i h line; The Vertical-line being grounded," the'cbnii'ectoi' "f ivertical 1ine-1'emy 'i'sjfnergi'zed, as 'stated",Yand. its armature ciiises' thelsp 'ings "3 27 and 3281 69 bepressed e sviitch wiper poin -i wnithez h m pj's tionwha m of 'f said srings energizes the i inger rel ay3lj5'. The 'cfirrent flows.fromtheQfOiihd tei miiml ll. con'n'e'cti andi S 2, the iingemgenertorli is bridged dii'ectlyfacifoss' the liIlFWiprS 25 1 and252, and, thefefore,"acroj s's the liiieofthe celled subscriber, withmeresmt that the ringer 'atj'th sub-station '#120j fis ener ized, V Thisperticnl a'rgenerator; er the control. of

h y t a onlyffthelbells {it the ab sg tan on will", nd; If the subseletqrii which een one of a rent of Whic' 'is' "capablepnlyg offringing 1con sta ipn V, ionly't s p rovi ed with" fingers that respond thi'oughthe condenser 4p2 '7 to the ringeryi28,

spring 432, vertical-line-conductor 517, nordllegi 'fi. different h'enjreached byc v P v29 the: a $1505. nl Tt thW p 5.11 'fr61' n which" pointit passes on to the normal:

fcoiidnctor 02, tIien'ceQ t'oQ the linercondnctorfli 516," spring 425,contactrpoint26', thence ith suchimeans and'connections, i1i= u knownmein1ier,-..either suhciribef chm-" 11y; and the subscribei-theie"answeitsby re- ,As' soon as, the calling hsiibscfibvep ttgn' 16Kthe iihgle r.

to press the signalifig- .7

andf the springs relay becomes dener moving his receiver 433Qf'rom the:hook 430,

31 8- and 321, respectively, *ren age ,Vwithl the springs317 ind '320,.it :WhiGh t'wo receivers 2" mid e333 mitt sub-stations 1 LO "%II I(1"heated in {the same be mmsyem cii'c'uit", beginning Withth'ef veceiv,

' sta rlit the respective be trdced through thegjsecongi ej'. W ndingthe springs 22 diidfzajt ofthefiieifticzthlineceiver433, contact-.pbint&26, spring 425 to the rotary-linejgc'ondlictorl j 516, thence vover:

482,15 thence onducton w,

line-wiper 251, conductor 505,-1side;s3vvzitch-= ductoi' 496,. pnvate-nomaLrelayi205 thence;

465, spring 37,- contzptrpoi'nh39, condenser- 15,1. hack to th'e"receive? 2; Y 1 'Ihe:inductioi1--- uit; omprisi'ng the -trmsmittecomprising the, transmitterAaihvbattery 442 pose of preventing suchinterference that I terminal G". The switch-hook-springsare isestablished part of the feature of my improved system will comeprominently into use if the subscriber at sub-station #2l0 attempts tomake a call. I have found in practice that if two party-lines'similar.to the ones represented in Fig. 1 are connected by means of..vs,witchingdevices of the character to which my improvement appliesthat-if afterthe saidconnection is established any one of the remaining substationson either line, by attempting to make a-call grounds either or both ofhis line-conductors, the. established connections will be broken by' thereleasing of the switches employed in making the connection. It is forthe purhave provideda non-interfering device, such as the one atsubstation #210, comprising the lock-out magnet 600. The connectionalready described being established, if a subscriber atthatstation-station #210+ removes his receiver from its hook, saidlock-out magnet will vbe operated so' as to prevent a connection betweenthe ground post60l or the signaling-button-contact 602 or the groundrelease-spring 603, and ground so adjusted that the springs 604 andwhich are normally disengaged when the switch-hook is down, as indicatedat substation #220, arethrown intoicontact as the switch-hook rises,before the spring 606 is separated from'the spring 6071 Since thefirst-selector is off-normal the rotary-lineconductor 465, which isnormally disconnected fromvthe non-grounded terminal of the battery B,is then connected with said battery through either one of severalcircuits, depending upon the position of thesideswitch-wiper 154 of thefirst-selector C, since the rotary-line-normal-springs 114 and 116 arethen' in contact. Therefore, there is in which a circuit through thelook-out relay 600 is completed, through which circuit 'a current fiowsthat will operatively -mag-- netizesaid relay. This circuit, when thefirst-selector side-switch is in the third position, and, therefore,when the subscribers line is extended to the connector, extends fromground- G through the, springs 606 and 607 to the lock-out relay 600,thence through the springs 604 and 605, contactpoint 608, spring 609,through the rotaryline-conductor 465, and thence through the springs 116and114, side-switch-wiper 154, conductor 495,-normal-relay 205,conductor- 496, rotary-line-wipe'r -101, rotary-trunkconductor 483,conductor 497, ringer-relaysprings 324 and 323, conductor 498, connectorrotary-line-relay 269 to the non- .ground'ed terminal of battery B andto ground G. The energization of this look out relay does not take placehowever until the switch-hook has risen sufiiciently to draw thelock-controlling rod 610 out of reach of the'lock piece 611.

At the instant that the relay 600 is mag- V netized the armature 612 isattracted by the pole-piece of therelay, which armature, as

it strikes the pole-piece, clears the lock piece 1 .611. The latter isforced up in front of said armature in such a manner that the armatureis locked against the pole-piece andretained there even after theenergizing current ceases toflow through the locking magnet. Saidarmature, being depressed, causes the spring 613 tobe separated from thespring 614 and thereby interrupts the continuity of the groundingconnection from the ground post 601, or the ground contactpoint 602, orthe release spring 603, to the ground terminal G even after. the groundsprings 615 and 616 are permitted to close. Therefore, the subscriber atthe sub-station #210 may work his calling device 'or-press hissignaling-button or hang up his receiver without interfering with theconnection existing at the time. It is not necessary for theside-switch-wiper 154 to pass into the third position, while the rotaryline offnormal springs 116- and 114 are closed in contact, in order thatthe lock-out magnet of the substation #210 may be energized, should thesubscriber at that'station .attempt a call. If the side-switch happensto be in the first position when the attempted call is made, theenergizing circuit, instead of passing from the side-switch-wiper 154 tothe conductor 495, and thence through the private-normal-relay 205to theiconnector, passes to the contact-point 178 and thence through therotary-line-relay 120 of the first-selector andbridge-cut-ofi-relaysprings 211, 212 and 213 to the non-groundedterminal of the battery B. -If the at tempted call occurs while theside-switch is in second position the energizing circuit, after reachingthe side-switch-wiper 154,

takes still another path which includes the, contact-point 200, theconductor. 494, the

vertical-line-relay 119, bridge-cut-oif-relaysprings 212 and 213 to thenon-grounded terminal of the battery B and to ground G. If thesubscriberdoes hang u his receiver before the subscriber at 'su station #110destroys his connection with the subscriber #120 the switch-hook 617,upon passing to its normal position, again separates the springs 604 and605, thus opening the energizing ,circuit through the look-out -magnet600. Immediately-after said springs are opened, the locking-rod 610 thendrives the locking piece 611 out of the way of the 7 lockingmagnet-armature 612, and the said; armature then returns to its normal,position, restoring the connection between the springs 613 and 614.Since the receiver 618, while the switch-hook is up, is bridged acrossthe line-conductors 465 and 454, the subscriber

